An ingredient is an object or item that is combined with other objects or items to create something. Usually the term 'ingredient' is used in relation to cooking food. For example, "Bill bought all the ingredients for his soup at the market." 'Material' can also be used similarly to 'ingredient' however is not used to describe what was cooked in a meal. Rather materials typically refer to non-edible things such as buildings, cars, toys, etc. Example: "The man bought materials to build his house at the store." In this example it would be incorrect to use the term 'ingredients' because you do not use food to build a house. I hope that explains the basics! :)

Basically ingredients is generally only used when you are talking about food, an exception though may be when talking about bombs for example : It had all the ingredients of a home-made bomb.